He says seven were above the recommended level of 0.01 micrograms per litre and one sample from Manna Hill was more than 10 times the level.

Residents say they were not notified of any testing, nor the results.

Mr van Holst Pellekaan says he asked SA Water Minister Paul Caica late last year for an explanation.

"I'm not aware that anyone was advised [of testing]. I've written to the Minister asking specifically 'Were the residents and users of water aware that the water should not be drunk?' and I've also asked very importantly what the Minister will do to ensure that this doesn't happen again," he said.

SA Water says the water quality in the four towns has been discussed with the SA Health Department.

It says under Australian Drinking Water Guidelines there are no immediate public health risks from short-term consumption.

It says the public would not normally be given advice unless contamination posed an acute health risk.